1. Field of the Invention
The present invention relates to a seat on which a person sits, and in particular, relates to a seat such as a seat for a means of transport or the like which is installed in a means of transport such as an automobile or the like.
2. Description of the Related Art
As seats for vehicles, there have been proposed seats in which a seat cushion is structured by stretching a tension structure, which is a three-dimensional solid knit fabric or a two-dimensional woven fabric or the like formed by a pair of ground knit materials and connecting threads disposed between the ground knit materials, over a frame for a sitting portion as a cushion material (see, for example, U.S. Pat. No. 5,013,089, and Japanese Patent Applications Laid-Open (JP-A) Nos. 2002-177099, 2002-219985 and 2003-182427). In such a seat, because the cushion material is structured by elastic threads which are difficult to weaken, the seat is thin and can achieve a good elastic characteristic (cushionability) as compared with a structure in which, for example, urethane is used as the cushion material.
However, in a conventional seat for a vehicle such as that described above in which a three-dimensional solid knit fabric and/or a two-dimensional woven fabric is stretched over the frame for the sitting portion, it is desired to obtain an even better elastic characteristic and to suppress vibration of the head portion of the seated person in particular.